linux-kernel - Re: linux-next: Tree for Apr 17 (objtool)

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Message-ID: <f430f7a9-ba11-5545-cfb6-59deb1ff8693@infradead.org>
Date:   Wed, 24 Apr 2019 12:54:39 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Peter Zijlstra <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Stephen Rothwell <sfr@...b.auug.org.au>,
        Linux Next Mailing List <linux-next@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: linux-next: Tree for Apr 17 (objtool)

On 4/24/19 9:22 AM, Peter Zijlstra wrote:
> On Wed, Apr 24, 2019 at 11:03:57AM -0500, Josh Poimboeuf wrote:
>> On Wed, Apr 17, 2019 at 08:41:34AM -0700, Randy Dunlap wrote:
> 
>>> on x86_64:
>>>
>>>   CC      drivers/gpu/drm/i915/i915_gem_execbuffer.o
>>> drivers/gpu/drm/i915/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x18: redundant UACCESS disable
> 
>> I haven't looked at this, do you know if this is the same issue as the
>> other note from Randy, or something else?
> 
> That smells like the below commit went missing... But I cannot reproduce
> when building next/master myself.
> 

This patch is already in linux-next of today & of the reported "problem."

> ---
> commit 8f4faed01e3015955801c8ef066ec7fd7a8b3902
> Author: Peter Zijlstra <peterz@...radead.org>
> Date:   Thu Feb 28 13:52:31 2019 +0100
> 
>     i915, uaccess: Fix redundant CLAC
>     
>     New tooling noticed this:
>     
>      drivers/gpu/drm/i915/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x3c: redundant UACCESS disable
>      drivers/gpu/drm/i915/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x66: redundant UACCESS disable
>     
>     You don't need user_access_end() if user_access_begin() fails.
>     
>     Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
>     Cc: Borislav Petkov <bp@...en8.de>
>     Cc: Chris Wilson <chris@...is-wilson.co.uk>
>     Cc: Josh Poimboeuf <jpoimboe@...hat.com>
>     Cc: Linus Torvalds <torvalds@...ux-foundation.org>
>     Cc: Peter Zijlstra <peterz@...radead.org>
>     Cc: Thomas Gleixner <tglx@...utronix.de>
>     Signed-off-by: Ingo Molnar <mingo@...nel.org>
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index 02adcaf6ebea..16f80a448820 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -1667,6 +1667,7 @@ static int eb_copy_relocations(const struct i915_execbuffer *eb)
>  					     len)) {
>  end_user:
>  				user_access_end();
> +end:
>  				kvfree(relocs);
>  				err = -EFAULT;
>  				goto err;
> @@ -1686,7 +1687,7 @@ static int eb_copy_relocations(const struct i915_execbuffer *eb)
>  		 * relocations were valid.
>  		 */
>  		if (!user_access_begin(urelocs, size))
> -			goto end_user;
> +			goto end;
>  
>  		for (copied = 0; copied < nreloc; copied++)
>  			unsafe_put_user(-1,
> @@ -2695,7 +2696,7 @@ i915_gem_execbuffer2_ioctl(struct drm_device *dev, void *data,
>  		 * when we did the "copy_from_user()" above.
>  		 */
>  		if (!user_access_begin(user_exec_list, count * sizeof(*user_exec_list)))
> -			goto end_user;
> +			goto end;
>  
>  		for (i = 0; i < args->buffer_count; i++) {
>  			if (!(exec2_list[i].offset & UPDATE))
> @@ -2709,6 +2710,7 @@ i915_gem_execbuffer2_ioctl(struct drm_device *dev, void *data,
>  		}
>  end_user:
>  		user_access_end();
> +end:;
>  	}
>  
>  	args->flags &= ~__I915_EXEC_UNKNOWN_FLAGS;
> 


-- 
~Randy